RHODODENDRONS
By Trey Pitsenberger, co-owner Golden Gecko

Most often when one thinks of the rhododendron the cool summer weather of the coast most often comes to mind. While the largest selection of rhododendrons does occur in cool summer climates, with careful selection these beautiful, and useful plants can thrive in the interior warm summer regions, like our foothills. The key is choosing the right varieties, the correct placement in the garden, and then giving them the proper care. Rhododendrons, especially the large leafed varieties are quite deer resistant.

You might be interested in knowing that rhododendrons include the small leafed plants we know as Azaleas. While we often separate Azaleas and Rhododendrons into separate categories, they are both members of the same family, Rhododendron. While as a general rule most azaleas have smaller leaves and flowers than Rhododendrons, we cannot as easily classify Rhododendrons. While many Rhododendrons have larger leaves and flowers than azaleas, some rhododendrons look more like azaleas than their larger leafed cousins. ‘Purple Gem’ rhododendron only grows 2’ high and 3’ wide. It holds azalea like foliage with purplish-blue blooms. Most people when shown this shrub will think it is an azalea.

Rhododendrons will tolerate early morning sun, filtered sun, or complete shade. This makes them great plants for the east or north side of the property, or as under story plants below trees. These plants require a rich acid soil that is both fast draining, yet is moisture retentive. In the foothills our soil is generally acid but poor draining. You will want to work in lots of organic matter before planting. Since rhododendrons are shallow rooted you must dig the hole three times the width of the container it comes in. Only dig the hole as deep as the container as the roots will never go more than a foot or so into the ground. Mix Master Nursery Planting mix with the dirt dug from the hole. You want a mix that is 75% Planting mix to 25% native dirt. Add a Starter fertilizer high in phosphorus, such as Master Start. Place the plant in the hole so that the top of the root ball is about a inch above the surrounding soil. Back fill with the soil mix. Since the roots grow shallow a mulch on top of the soil will help keep the roots cool and moist thru the hot months.

Many people assume that all rhododendrons become quite large. While some varieties do get as tall as seven feet plus, there are a large variety that stay compact and small, some only growing a couple of feet tall and wide. ‘ Cunningham’s Blush’ has blush pink funnel-shaped flowers in spring. The plant grows wider than tall, four feet tall by six feet wide. ‘ Daphnoides’ has foliage unlike any other Rhododendron. Rolled glossy leaves are tightly spaced on stems of this dense mounded plant. Prolific pompon trusses are purple. This plant is very effective as an accent. ‘Daphnoides’ is a moderate grower to 4 feet tall and wide. Growing only to about three feet tall and wider is ‘P.J.M.’ This variety stands up well to heat, and has bright lavender pink blooms. ‘Rosamundi’ grows to about four feet tall and wide and has pretty light pink flowers with very dark green leaves. The above varieties do well in the foothills with our hot dry summers and cool winters. There are many other types suited for our area. The above are some of my favorites.

When watering rhododendrons, frequent watering is better than deep watering, infrequently. We are not trying to get the roots to grow deep. That’s against the nature of the plant. Use mulch underneath these plants. Fir mulch or shredded cedar are great for keeping the roots cool and moist. You want to water frequently enough that you could keep moss growing underneath. Feed rhododendrons a couple of times in the spring with an acid food.

Rhododendrons are suited for most areas of the foothills, from the lower elevations to the higher mountain regions. If you have a shady area, that could use some good foundation plants that provide a fantastic flower show in the spring, rhododendrons just might be the plant for you.